Weather Service Report

FXUS66 KPQR 202110

Area Forecast Discussion
National Weather Service Portland Oregon
209 PM PDT Thu Oct 20 2016

.SYNOPSIS...A rather moist and fairly active cold front will continue
to move through southwest Washington and northwest Oregon for periods
of rain and some coastal breezes this afternoon, then linger over
eastern Lane and Linn counties tonight into Friday before dissipating
during the day Friday as weak high pressure builds into the forecast
area. The next disturbance will bring some showers onshore Friday
afternoon and evening, with drier weather possible Saturday. The next
cold front will move onshore Saturday night ahead of a broad, cool
upper low from Alaska that will set up off the Pacific NW coast
Sunday and continue near the coast and produce unsettled weather into
at least the first half of next week.

.SHORT TERM...Tonight through Sunday...A cold front was moving
through the Portland area around noon to 1 pm this afternoon. The
front will continue moving south and east through northwest Oregon
this afternoon as a wave evident on IR satellite imagery along the
front moves through the area. The models continue to say the front
will linger tonight into Saturday in eastern Lane and Linn counties
with some steadier precipitation that gradually decreases, but areas
to the north and west will be drying out with perhaps some patchy fog
developing later tonight and Friday morning. There are not many
showers immediately behind the front so shower coverage tonight and
early Friday will be on the sparse side.

The main area of showers and instability are located well to our
northeast near 50N/140W and are associated with the parent low to our
current front. These showers approach our forecast area Friday,
perhaps not spreading onshore until Friday afternoon and Friday
evening. The models indicate some instability over the coastal waters
and along the coast and have some thunder mentioned there, but this
is not indicated for inland areas at this point.

The next disturbance looks to spread a front toward the coast by late
Saturday and especially Saturday night, but inland areas are looking
relatively dry Saturday after some local areas of morning fog. The
front will likely still be over southwest Washington and northwest
Oregon on Sunday and produce some more showers before weakening. The
parent low will be setting up off the coast by fairly early Sunday,
and will continue to produce unsettled weather into at least early
next week. Tolleson

.LONG TERM...(Sunday night through Thursday)...Rainy pattern
continues, though no big storms on the horizon. As normally occurs in
this type of pattern, there has been a significant change in the
track of the Low that sets up off the coast of Washington and Oregon
over the weekend. Now, the Low is expected to track north into
Vancouver Island, which will keep snow levels higher than previously
forecast for early next week. This Low isn't forecast to get deeper
than 985 mb, and should remain well offshore, so not expecting it to
get more than a little breezy along the Coast next week. With regard
to rain next week, there will be a cold front that moves across the
area on Monday, bringing another round of moderate rainfall across
the area, with higher amounts expected in the Central Coast Range of
Western Oregon, South Willamette Valley, and Central Oregon Cascades.
On Tuesday, the occluded Low bends back and sends through a secondary
front associated with the bent-back occlusion for a round of moderate
showers. Broad troughing remains over the Northeast Pacific and
Pacific Northwest, with precipitation continuing through midweek.
Details become much less certain by Wednesday, though pattern
suggests rain will continue through at least Thursday. -McCoy

.AVIATION...Cold front now extends from near KTTD to KSLE to just
south of Florence. Front will slowly push farther east and south, but
will stall tonight and weaken. Generally MVFR along and ahead of the
front, with those conditions persisting tonight over good part of
inland Lane county northward along the Cascade Foothills. Farther
north and along the coast, clouds will continue breaking up through
this evening, but will keep a few showers around. Clearing areas
should be large enough to allow areas of fog and/or low clouds to
form later tonight.

KPDX AND APPROACHES...VFR with occasional brief MVFR cigs for rest of
this afternoon, but clouds gradually breaking up after 00z. With wet
ground and light winds, any clearing should allow areas of fog
and/low clouds to form. Likely to get IFR conditions after 10z...and
lasting into Fri am.       Rockey.

.MARINE...Cold front now onshore in northwest Oregon, but still lies
from Florence back to southwest over the Oregon coastal waters around
Florence. Now much more benign conditions over the coastal waters,
with winds under 15 kt and seas 7 to 8 ft through Fri afternoon. 

Broad area of low pressure remains over the Gulf of Alaska into early
next week. This will maintain active storm track across the north Pac
and into the Pac NW. End result is a series of fronts will continue
to move across the region. Next will be a weak front late Fri, with a
somewhat stronger front arriving late Sat and Sat night. Some
potential that that Sat system will bring a round of low-end
southerly gales, with seas back at 12 to 15 ft. Another front arrives
later Sun. Rockey. 

PZ...Small Craft Advisory for Rough Columbia River Bar from 6 PM to 
11 PM this evening.



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This discussion is for Northwest Oregon and Southwest Washington
from the Cascade crest to 60 nautical miles offshore. The area is
commonly referred to as the forecast area.

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